This invention relates to a mechanical telephone conversation time limiting device.
It is known that the costs for telephone utilities reach considerably high figures, both in the business and domestic fields; also known is that such costs, while presently as far as intercity calls are concerned but most probably infracity calls as well within the next future, are proportional to the duration of the conversations. Moreover, it will be recognized that the duration of telephone conversations is very often unduly prolonged beyond strictly necessary limits: it can be observed, in fact, for instance on the occasion of business telephone calls, that little importance is given to the incidence of telephone calls, whilst more time is frequently wasted on preliminaries, digressions and superfluous formalities than is spent to communicate information of substantial value. This reflects in practice in out-of-proportion telephone expenses as well as useless and costly distraction of employees from their job.
Those devices, currently available on the market, which disable a telephone set when a call is effected (i.e. which only allow calls to be received), fail to solve the second of the above problems (time substracted to the corporation) and cannot be always utilized because it is often required that employees make telephone calls.
On the other hand, known are devices for automatically interrupting a telephone conversation which are so constructed as to be applicable to a standard telephone set. These devices, which are known in particular from U.S. Pat. Nos. 2,202,149, 2,609,045 and 3,472,966, comprise a case or housing intended for attachment to the telephone set and containing a mechanical timer which is started upon the handset being raised to make a call. The timer, upon expiration of the time interval to which it has been set or designed, acts on one or more movable members effective to interrupt the conversation by acting on one shut-off pushbutton of the telephone set to depress it.
The casing can be secured to the telephone set by means of a key-operated padlock, and may be configured to prevent access to the shut-off pushbuttons of the set when the casing is attached to the set, as described in the above mentioned U.S. Pat. No. 3,472,966. In all cases, in spite of such features, these devices have the drawback that they can be easily thwarted, in that they allow, during the telephone conversation, the timer to be reset indefinitely, thereby one is enabled to avoid the interruption of the conversation and can carry it on at will. Another drawback of these devices is that they have a complex construction and not always operate exactly at the preset time.
Also known are devices which are operative to interrupt a telephone conversation after a preset time lapse, which rather then utilizing mechanical members, make use of electronic elements and circuits. A device of this type is disclosed in French Pat. No. 2,272,551. This device operates on the telephone line itself as actuated by a signal emitted on that line. However, it requires therefore manipulation of the telephone line, and is difficult to install and use without undergoing penalties or meeting the opposition of telephone companies.